Process of precipitating and recovering materials from solutions.



0. W. MERRILL. PROCESS OF PBEGIPITATING AND REGOVERING MATERIALS FROM SOLUTIONS.

APPLIGATION FILED NOV. 23, 1906. RENEWED JULY 29, 1908. 900, 1 86.

Patented Oct. 6, 1908.

o a a INVENTOR UNITED STATES PATENT-OFFICE.

. CHARLES w. MERRILL, or LEAD, sou'rn DAKOTA.

mtocnss or rnncrnrawma m ancovrznme MATERIALS snou soLirnoN's.

Specification of Letters Patent.

Patented Oct. c, 1908.

Application med-nointa as, 19cc, Serial at. 344,701. Renewed July 29,1908. Serial No. 445,926.

To all whom it may concern: I

Be it known that I, CHARLES W. MERRILL, a citizen of theUnited States, andresidcnt of Lead, county'of Lawrence, 'and'State of South Dakota, have invented a new and useful Improvement in Processes of Pre cipitating and Recovering Materials from Solutions, of which the following is a specification.- I v .1 I

My invention relates to animproved process of preci itating and recovering valuable materials rom solution, and: particularly metals from hydro-metallurgical solutions.

In ractice, metallic zinc bearing materials or su fids of zinc have heretofore been used to precipitate metals from cyanid solutions by agitating such precipitants from such solutions in an open tank and subsequently passing the mixturethrough a filter. This method is open to many disadvantages;

among others that the precipitant must remain in contact with the solutlon for the .Whole eriod required to remove the mixture from t e tank and by reason thereof the mixture comes in contact with the atmosphere during the said period. Again, an u n, necessarily arge amount of 1 precipitant is dissolved by. the solution during tlus period, and an unnecessarily large amount of solvent, such as alkali or alkaline earth metal cyanid is decomposed during said period. A redissolving of the precipitate takes place during said period, and the loss of chemicals and the re-solution which is in many cases romoted by the contact, with the atmos ere during the said period is a matterfo considerable importance. Moreover, a it has been ascertained that in practice, in agitating the mixture of precipitant and solution and subsequently wlthdrawin the mixture, after a portion of the mixture as been withdrawn, a re-solution of. the-preclpitate, :par-

ticularly in the upper zone of the mlxture in the tank, has taken place. Now, Ihave discovered that when a suitableprecipitant is added to a movingbody of solution such as a metal bearing cyanid solution, and the mixture is conducted without rest or without contact with the atmosphere, or both, to a filter, preferably'apressure filter of the type described by me in thea plication hereto fore filed by me in the United States ,Patent Ofiice under Serial Number, 322,388, that most of the disadvantages above referred to are obviated and very much more efiicient results are produced. I a v r and other metals.

views. I

.iIn'casecollecting tanks are introduced between the containers in which the dissolution, partlcularlyof the recious metals from thefcrushed ore, takes p ace, and the filter, I add the preclpltant to the solution as it leaves the collecting tank or at some point between the collecting tank and the filter, or

I may add'it to the filter direct. In the absence of collecting tanks, I add the precipitant to, the moving solution at some point between the crushed ore and the filter, or to the filter direct. In practice cyanid solutions resultant from t 1e treatment of ores contain, in addition to the gold and allied metals, another group such for example as silver, lead, mercury, etc., which may be precipitated, at least in part, as sulfids; In some such cases it is'very desirable to precipitate the latter group, at least in part, before proceeding to precipitate the go d, the remainin silver,

This I accomplish addition'of a sulfid soluble in solutions of an alkali or an alkaline earth metal cyanid which isaddedeither directly as an alkaline sulfid or formed in the cyanid solution to be precipitated, and containing free alkali, by

by the cipitated metals, and also to re-combine the I cyanogen thus liberated as an alkali metal or alkaline earth metal and leave the solution in better condition for the precipitation oftheremaining metals by the second precipitant.

After the aforesaid metals have been elimi .nated at least in part, and gold and other -unprec1p1tatedmetals only are present, I

derstood by reference to the accompanying sheet of drawings formin a part of this specification, in which. simi ar letters refer to similar parts throughout the said several for the preci itant.

H is the not through which the precipitant is conveyed to the unprecipitated solu- F is a filter press shown, in this case, with the feed inlet at the toiand with open delivery into the launder which discharges into the receiver E for preci itated solution.

'said filter.

The particular method w ich I prefer to use is as follows: The receiver U having been filled with solution, the precipitant 1n the shape of an emulsion or solution is added to the receiver Z. A flow of liquid-is then started through the pipe I to the bottom of the receiver Z which then discharges its contents gradually through the duct H which leads to a point adfiicent to the inlet of the suction pipe 0. Te pump is then started and the mixture of solution to be precipitated and the recipitant is drawn into the suction pipe C, t ence through the pump P, thence through the discharge pi e D, and thence through the filter F, whic retains the precipitate and permits the precipitated solution to pass into the launder L and thence to the receiver E.

I do not limit myself to any particular method of conducting the unpreci itated solution from the container in which t e dissolution'takes place to the filter, nor do I limit myself to adding the precipitant at any point along the duct through which the efiiluent unprecipitated solution asses from thedissolvin container to the filler; nor do I limit mysel? to the use of the precipitant in a liquid or emulsified form, but may add it 1 claim as my invention:

1. The process for precipitating and recovering material from 1ts solution which consists in adding a precipitant to said solution while in. motion, conducting the mixture without rest to a filter, and separating the solid from the liquid in said filter.

I 2. The process for precipitating and recovering iiiaterial from its solution whlch consists in adding a recipitant to the duct through which said solution is being conveyed to a filter and separating the solid from the liquid in said filter.

3. The process for precipitating and recovering material from its solution which consistsin conveying said solution to a pressure filter, simultaneously forcing a precipitantinto said pressure filter with said solution and separating the solid from the liquid in said filter.

4. The process for precipitating and recovermg material from its solution which con-- sists in addin a precipitant to the duct in which said so ution is conveyed, forcin the mixture into the bottom of a pressure filter, and separating the solid from the liquid in 5. The process for precipitating and recovering material from its solution, which consistsin adding a precipitant to a solution in motion at a point'adjacent to the outlet of said solution from a receiver, forcing the mixture throu h a pressure filter, and separatin the soliffrom the liquid in said filter.

6. The'process for precipitating and recovering material from its solution which con sists in adding a precipitant to said solution inmotion, convefiing the mixture to a filter, and se arating t e solid from the liquid in said ter, all the while excluding the mix ture from contact with the atmosphere.

7. The process for precipitating and recovering material from its solution which consists in adding a precipitant to said solution in motion at a point adjacent to the suction pipe of a pump, thence pumping the mixture to the bottom of a pressure filter, and separating the solid from the liquid in said filter.

8. The process for precipitating and recovering material from its solution which consists in adding a precipitant to said solution in motion at a point adjacentto the suction pipe of a pump, thence pumping the mixture to the bottom of a pressure filter and separating the solid from the li uid in said filter, all the while excluding t e mixture from contact with the atmosphere.

9. The process for precipitating and recovering metals from a cyanid solution which conslsts in addin vided zinc to said solution while in motion, conducting the mixture without rest to a filter, and se arating the solid from the liquid in said ter.

10. The process for preci itating and recovering metals from cyani solutions which consists in addin an emulsion of finely divided zinc to said solution while in motion conducting the mixture to a filter and separating the solid from'the liquid in said filter, all the while excludin the mixture from contact with the atmosp ere.

11. The process of preci itating and recovering metals from cyanid solutions which consists in mixing finely .divided zinc with a liquid in a receiver, addin a liquid continuously to said receiver, disc arging the emulsion from said receiver into said solution in motion, conducting the mixture without rest to a filter, and separating the solid from the liquid in said filter.

12. The process for precipitating and recovering metals from cyanid solutions which consists in mixing finel divided zinc with a liquid ina receiver, ad in a liquid continuously to said receiver, disc arging the emulsion from said receiver into said solution in motion, conducting the mixture without rest to the bottom of a converging pressure filter, and separating the solid from the liquid in said filter.

13. The process for precipitating and recovering metals from cyanid solutions, which an emulsion of finely di- I consists in adding a sulfidsoluble in solutions of an alkali or an alkaline earth metal cyanid to said solution, whereby certain of the metals contained therein, are precipitated at least in part subsequently adding to the solution, a suitable precipitant for precipitating the gold and other unprecipitated metals, conducting the mixture to a filter, and separating the solid from the liquid in said filter. 1

14. The process .for precipitating and recovering metals from cyanid solutions which consists in first adding a sulfid soluble solutions of an alkali or an alkaline earth metal cyanid to said solution and subsequently adding finely divided zinc to said solution conducting the mixture to a filter and separating the solid from theliquid in said filter.

15. Theprocess for precipitating and recovering metals from cyanid solutions which consists in first adding a sulfid soluble in solutions of an alkali or an alkaline earth metal cyanid to said solution and subsequently adding finely divided zinc to said solution conducting the mixture Without rest toa filter and separating the solid from the liquid in said filter. i

16. The process for precipitating and recovering metals fromcyanid solutions which' consists in first adding asulfid soluble in solutions of an alkali or an alkaline earth metal cyanid to said solution and subsequently adding finely divided zinc to' said solution conducting thejmixture excluding in said divided zinc to said' filter and separating the solid from the liquid filter.

18. The process for precipitating and recovering metals from cyanid solutions which consists in adding a sulfid soluble in solutions of an alkali or an alkaline earth metal cyanid to said solution whereby certain of the I metals contained therein are precipitated, conducting this mixture to a filter, separating the solid from the filtrate in said filter, subsequently adding to the filtrate a suitable precipitant for precipitating the gold and other .unprecipitated metals, conducting this mixture to a filter and separating the solid from the liquid in said filter.

In testimony, that I claim the foregoing as my invention, 1 have signed my name in presence of two Witnesses, this 16th day of November 1906.

CHARLES W. MERRILL.

Witnesses: S. MERRILL, WM. HAMMOND, Jr. 

